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Abstract:

An optical disc having a region with pre-recorded data and a recordable
region, a method of fabricating the disc, a stamper for forming a disc
master, and a recording device for use with the disc are disclosed. Data
recorded in the recordable region may be used for activation of the disc,
providing unique identification or enhancing program content on the disc.

Claims:

1-17. (canceled)

18. An optical disc, comprising: a first region with pre-recorded data
formed on a substrate; a second region including one or more recordable
areas having at least one groove; and a recording layer formed only in
the second region; wherein the pre-recorded data and the recording layer
are located on a single data layer.

19. The optical disc of claim 18, wherein the at least one groove has a
depth of less than about 100 nm.

20. The optical disc of claim 18, wherein the at least one groove has at
least one discontinuity.

21. The optical disc of claim 18, further comprising a reflective layer
contacting at least the substrate in the first region, and contacting at
least the recording layer in the second region.

22. A method of fabricating an optical disc, comprising: (a) forming a
first region with pre-recorded data on a substrate; (b) forming a second
region with at least one groove on the substrate; and (c) forming a
recording layer only in the second region; wherein the pre-recorded data
and the recording layer are located on a single data layer.

23. The method of claim 22, wherein the at least one groove has a depth
of less than about 100 nm.

24. The method of claim 22, wherein the at least one groove has at least
one discontinuity.

25. The method of claim 22, wherein steps (a) and (b) are performed by
molding the substrate using a stamper containing features corresponding
to the pre-recorded data and the at least one groove.

26. The method of claim 22, wherein step (c) is performed by masking the
first region and applying a recording medium of the recording layer by
spin coating.

27-30. (canceled)

31. The method of claim 24, wherein the at least one discontinuity
includes a plurality of gaps, each gap having a length of at least 75 nm.

32. The method of claim 24, wherein the at least one discontinuity
includes a plurality of gaps, each gap having a length of less than about
200 nm.

33. The method of claim 24, wherein the at least one discontinuity
includes a plurality of gaps, each gap having a length sufficient for
differential phase detection tracking.

34. The optical disc of claim 20, wherein the at least one discontinuity
includes a plurality of gaps, each gap having a length of at least 75 nm.

35. The optical disc of claim 20, wherein the at least one discontinuity
includes a plurality of gaps, each gap having a length of less than about
200 nm.

36. The optical disc of claim 20, wherein the at least one discontinuity
includes a plurality of gaps, each gap having a length sufficient for
differential phase detection tracking.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to a U.S. Provisional Application,
Ser. No. 61/066,305, "Secured Hybrid Pre-recorded and Recordable Disc"
filed on Feb. 19, 2008, which is herein incorporated by reference in its
entirety.

TECHNICAL FIELD

[0002] This invention relates to storage media in the form of an optical
disc.

BACKGROUND

[0003] Pre-recorded optical media (e.g., optical discs) can be
mass-replicated inexpensively and constitute an ideal distribution medium
for many types of data, including, for example, compact disc (CD)-Audio,
digital versatile disc (DVD)-Video, CD read-only memory (CD-ROM), Blu-ray
discs (BD). Many optical disc applications can be enhanced or made more
secure if the pre-recorded discs are made unique or serialized such that
a typical readout device can identify the unique information. This is
currently only possible with recordable media that has an added expense
associated with recording, or on pre-recorded media via Burst Cutting
Area (BCA) code writing for DVD, BD, and so on, where BCA has limited
data capacity and limited application compatibility.

[0004] A proposed alternative for improving disc security involves the use
of radio-frequency identification (RFID) technology, in which an optical
media with pre-recorded content is provided with an electro-optic layer,
which allows the media to be disabled at a manufacturing facility, and
subsequently enabled at a point of sale using RF activation. There is,
however, still a need for additional techniques for disc activation in a
manufacturing, a distribution or a retail setting,

SUMMARY OF THE INVENTION

[0005] Embodiments of the present principles provide an optical disc
having pm-recorded and recordable regions, various groove structures or
configurations, as well as method of forming the disc, a stamper for
forming a disc master, and a recording device for writing data to the
recordable region.

[0006] One embodiment provides an optical disc, which includes a first
region with pre-recorded data including program content, and at least one
recordable region. The program content is unreadable until additional
data is written to the recordable region.

[0007] Another embodiment provides an optical disc, which includes a
recordable region having at least one groove with a plurality of gaps, in
which the at least one groove is configured for use in recording data.

[0008] Another embodiment provides an optical disc, which includes a
recordable region having at least one grooveless region, in which the at
least one grooveless region is configured for recording data.

[0009] Another embodiment provides an optical disc, which includes a first
region with pre-recorded data formed on a substrate, a second region
including one or more recordable areas having at least one groove; and a
recording layer formed only in the second region.

[0010] Another embodiment provides a method of fabricating an optical
disc, which includes:

(a) forming a first region with pre-recorded data on a substrate, (b)
forming a second region with at least one groove on the substrate, and
(c) forming a recording layer only in the second region.

[0011] Another embodiment provides a stamper for use in fabricating
optical discs, which includes features for forming at least one groove
and a plurality of pits on the disc, in which the features include at
least one of: forming a groove having a plurality of gaps, and forming a
blank section with a length greater than about 10 μm and less than
about 100 μum between two pits.

[0012] Another embodiment provides a recording device, which includes a
processor configured for executing a program having instructions for
performing a method, the method including retrieving information for
identifying at least one recordable region of a disc by one of: accessing
pre-recorded data on the disc, and accessing a database external to the
disc; and directing a laser to write additional data to the at least one
recordable region.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The teachings of the present invention can be readily understood by
considering the following detailed description in conjunction with the
accompanying drawings, in which:

[0014] FIG. 1 illustrates a top view of an optical disc according to one
embodiment of the present invention;

[0022] FIG. 5e is a top view of an optical disc having areas with
different groove arrangements;

[0023] FIG. 6a is a top view of one embodiment of a disc having
discontinuous grooves according to one embodiment of the present
invention;

[0024] FIG. 6b is a perspective sectional view of two discontinuous
grooves;

[0025] FIG. 7a is a top view of a disc according to another embodiment;
and

[0026] FIG. 7b is a perspective sectional view of a blank section in a
recordable area.

[0027] To facilitate understanding, identical reference numerals have been
used, where possible, to designate identical elements that are common to
the figures.

DETAILED DESCRIPTION

[0028] Embodiments of the present principles provide an optical disc
having pre-recorded and recordable regions (also referred to as a
"hybrid" disc), a method of fabricating the disc, as well as a disc
master and stamper that include various features in the pre-recorded and
recordable regions, and a recording device for recording data in the
recordable regions of the disc. A pre-recorded region refers to a region
containing data that is formed during manufacturing of the disc. Such
pre-recorded data may include control data, file systems, and program
content representing the subject matter of the disc, e.g., software,
audio and/or video content, or other content intended for the user(s) of
the disc.

[0029] One or more recordable regions, which may include structures
different from those of conventional discs, are provided for the
recording of additional data. The additional data may include
predetermined data required for disc activation so that content on the
disc can be made readable or accessible to end users, for disc
serialization or customization, for providing enhancements or updates to
the disc's pre-recorded content (e.g., may be appended to the existing
program tile/content), and so on. The additional data to be written to
the disc is usually a relatively small amount compared to the
pre-recorded program content. Furthermore, if the pre-recorded program
content is in encrypted form, the additional data may include decryption
information, e.g., a decryption key, which can be written to at least one
recordable region of the disc to render the program content readable. The
additional data may be written using a custom recording device at a
facility in a product distribution chain or at a point-of-sale.

[0030] The optical disc is initially manufactured (e.g., replicated or
duplicated) with a region of the disc containing pre-recorded data and at
least a region of the disc being unrecorded but available for recording
of data with a suitable recording device. In the case of a replicated
disc, the pre-recorded data is formed by stamping into a substrate of the
disc as with injection molding, and a reflective layer is provided for
reading the pre-recorded data, as in conventional pre-recorded discs.

[0031] However, unlike a conventional pre-recorded disc, a recording layer
is also applied to the molded substrate before bonding with a top
substrate. The recording layer provides additional recording space for
completing the recording in a subsequent recording device and process,
which is performed offline, i.e., after the disc manufacturing process.
Thus, the recording device for performing the finalization is different
from the device used to encode the pre-recorded data.

[0032] The resulting pre-recorded disc has a capability and capacity to be
individually written to or "serialized" with unique, custom and/or
control data during the offline recording or finalization process. The
finalized disc will be recognized by conventional optical disc drives as
pre-recorded with no ability for further writing or recording. Such a
finalizing process may be used for controlled activation of the disc,
i.e., at least the pre-recorded program content is not readable until
appropriate data, e.g., control or unique data are written, and the
finalization process has been successfully completed. This finalization
process requires the correct or appropriate information being recorded,
in order for the disc and its program content to become readable by an
end user's disc player. Unlike conventional finalization processes in
which information is written to the lead-in or lead-out areas after
recording, the finalization process according to the present principles
may record information outside the lead-in and lead-out areas. Thus,
pre-manufactured discs can be securely distributed to end users,
distribution centers or point-of-sale kiosks, which can finalize the
discs with appropriate secure recording devices.

[0033] The additional data to be recorded in the finalization procedure
may include disc activation data, custom data for augmenting or updating
program content on the manufactured disc (including data that allows the
program content to be usable), unique product information or code that is
individually serialized, control data, or file system data. For encrypted
program content, a decryption key may also be required to be written to
the disc before the program content becomes readable. As used herein,
"custom" data refers to any data that is recorded to the information area
of the disc, which may include control data, or serialization data, or
other data that is custom or unique to the disc. "Control" data may
include physical format information, disc manufacturing information and
contents provider information.

[0034] FIG. 1 shows a top view of an optical disc 100 after manufacturing
(but before finalization) according to one embodiment of the present
invention. The optical disc 100 may generally be any optical disc, e.g.,
CD, DVD or Blu-ray disc, with program content data, e.g., video, audio,
software or other data, recorded in a continuous spiral pattern 102, with
each 360' turn of the spiral forming a track. For the sake of clarity,
intermediate tracks of the spiral are omitted from FIG. 1 and designated
by a dashed line. A lead-in area 104 is provided at the beginning of the
spiral 102, and a lead-out area 106 is provided at the end of the spiral
102. The lead-in area 104 generally contains a control data zone, which
contains control data such as the physical format information, disc
manufacturing information and contents provider information. By reading
this control data, a disc player can then access the user data content
(e.g., pre-recorded program such as a movie, software, and so on) of a
disc. For a recordable disc, data is written to the lead-in area when a
recording session is closed. In one embodiment of disc 100, the lead-in
area contains both pre-recorded control data and at least one recordable
area for recording additional control data. The lead-out area 106
indicates the end of data on the disc 100, and typically does not contain
any data.

[0035] The portion of the spiral 102 between the lead-in and lead-out
areas may be referred to as a program area 105, which contains data
corresponding to one or more programs on the disc 100. Aside from the
recorded program data, one or more recordable areas or regions 110, 120
and 130 are also provided between the lead-in and lead out areas 104 and
106. These recordable areas, which may also correspond to individually
accessible sectors on the disc, allow additional data to be recorded at a
later stage, i.e., after the disc 100 has been manufactured. In various
embodiments, the recordable zones may be identified by sector numbers,
signal characteristics and/or custom zone identifiers which can be used
for guiding a recording device to the proper recordable locations during
recording. These identifiers, or information relevant to the recording
process, are different from control data or information in conventional
optical discs. They may be provided (during the manufacture process)
anywhere in an information zone on the disc, and may also be available in
the form of a database in a storage device (outside the disc) and
accessible by a disc reader. As used in this discussion, the term
"information zone" refers generally to any region of the disc where data
is present, including pre-recorded and later recorded data. In one type
of dual-layer discs, the information zone also includes middle zones
(i.e., transition regions between two data layers) that have dummy data
used for optical pickup and addressing purpose.

[0036] Since program data in area 105 is encoded on the disc 100 during
manufacturing, e.g., by molding of a substrate, it is referred to as
"pre-recorded" data, to distinguish it from data that may be recorded in
areas 110, 120 or 130 at a later stage.

[0037] FIG. 2 is a sectional view from an inner diameter ID to an outer
diameter OD of the disc 100, showing representative recordable regions
120, 130 and pre-recorded area 105 between the lead-in area 104 and
lead-out area 106.

[0038] FIG. 3a shows a cross-sectional view (e.g., from inner diameter ID
to outer diameter OD) of various material layers of an optical disc 300A
manufactured according to one embodiment of the present invention. The
disc 300A has a first substrate 302 having pits and lands 304, 306, one
of which representing data, e.g., corresponding to data in the program
area 105 of FIG. 1. The substrate 302 is further provided with one or
more grooves 308 in at least one recordable region of the disc 300, e.g.,
corresponding to regions 110, 120 or 130 in FIG. 1. These grooves are
absent in pre-recorded areas with pits and lands. The substrate 302 is
usually made of a transparent material that allows optical access for
reading data on the disc, e.g., polycarbonate or other suitable
materials. In one embodiment, the pits, lands and grooves on substrate
302 are formed by molding the substrate 302 with a stamper (to be
discussed below) using techniques known in optical disc manufacturing.

[0039] A recording layer 310 is then formed over the molded substrate 302,
e.g., by spin coating. Suitable recording medium or materials for the
recording layer 310 include organic, inorganic or phase change materials.
In one embodiment, the recording layer 310 is deposited over the entire
surface of the substrate 302, i.e., over the pre-recorded area of the
pits 304 and lands 306, as well as the recordable areas with grooves 308.
A reflective layer 320 is then deposited over both the pre-recorded areas
and the recordable areas by sputtering. Depending on the specific disc or
applications, different materials such as silver, silver alloy, aluminum,
among others, may be used in forming the reflective layer. The thickness
of the recording layer 310 and the reflective layer 320 also vary
according to the specific materials and the type of optical discs being
manufactured.

[0040] After the formation of the reflective layer 320, an adhesive or
bonding layer 330 is used to bond the metalized structure of substrate
302 to a top substrate 340, which is typically another transparent
material, e.g., polycarbonate.

[0041] In another embodiment, the recording layer 310 is formed only over
certain region(s) of the disc 300, e.g., by masking the pre-recorded
region(s) of the disc 300 and sputtering the recording layer 310 such as
inorganic or phase-change materials onto the unmasked region(s).
Alternatively, a suitable recording medium may also be selectively
applied by spin-coating to certain areas of the disc.

[0042] This is illustrated in FIG. 3b, which shows a cross-sectional view
(e.g., from inner diameter ID to outer diameter OD) of a disc 300B having
a recording layer 310' formed over only a selective portion of the
substrate 302'. In this example, region R1 of the substrate 302°
is masked before the recording layer 310' is deposited onto the substrate
302 in only region R2. Region R1 may include all portions of the disc
with pre-recorded data, and region R2 may correspond to an outer portion
of the disc 300B that includes all recordable areas. After forming the
recording layer 310', the mask (not shown) is removed before forming the
reflective layer 320' over the entire disc 300B. Similar to the example
of FIG. 3a, a top substrate 340' can be bonded to the reflective layer
320' using a bonding layer 330'.

[0043] Another example is shown in FIG. 3c, which is a cross-sectional
view (e.g., from inner diameter ID to outer diameter OD) of a disc 350,
e.g., a Blu-ray disc, with one or more pre-recorded data region(s) and at
least one recordable region with one or more grooves for recording
additional data. In this example, pits 354 and lands 356 (representing
pre-recorded data) as well as one or more grooves 358 in a recordable
region are formed in a substrate 352. The substrate is a 1.1 mm
polycarbonate, and the data and groove features may be formed by
injection molding and stamping. A reflective layer 360 is formed over the
substrate 352. A region R1 of the substrate structure is masked off, and
a suitable recording layer material (e.g., inorganic or phase change
materials) is deposited onto the unmasked region R2 of the reflective
layer 360, resulting in the formation of the recording layer 370. A cover
layer 380, e.g., 0.1 mm of a suitable material, is then formed over the
entire structure. In the case of the Blu-ray disc, data is read from the
side of the cover layer 380.

[0044] Although the above examples pertain to a single layer disc,
principles of the invention can be extended to a double layer disc. Thus,
one or both layers of a double layer disc may contain recordable areas
with associated recording grooves. If recordable areas are present in
only one of the two data layers, the other layer can be manufactured
using conventional techniques. In addition, other embodiments also
include having the pre-recorded area on one layer and the recordable area
on a different layer.

[0045] As mentioned above, a stamper is used to form the various features
in the molded substrate. One embodiment is illustrated in FIG. 4, showing
a portion of a stamper 400 having features that are complementary to
those on substrate 302 of FIG. 3a, e.g., protrusions 404 for forming pits
304, indents 406 for forming lands 306, and protrusions 408 for forming
grooves 308. Absent from the stamper 400 are features corresponding to
the additional data, e.g., control data or other data in the lead-in
and/or other recordable areas of a manufactured disc that are required to
render the disc readable. In general, a stamper of the present invention
includes features for forming one or more recording grooves on a disc,
and data tracks characterized by pits and lands. The recording groove(s)
may have different structures and/or configurations that will be
presented in later sections of this discussion.

[0046] The stamper 400 can be made using conventional techniques and
materials known in optical disc manufacturing. In one embodiment, the
stamper 400 is made by electroforming a metal, e.g., nickel, over a
metalized glass master, which has data and groove features that are
complementary to those of stamper 400.

[0047] FIGS. 5a, 5b and 5c illustrate schematically the fabrication of a
metalized glass master that may be used for forming features of the
stamper 400 (FIG. 5a-c show only the cross-sectional views of features
corresponding to those in FIG. 4). FIG. 5a shows a blank glass substrate
500 provided as a carrier for a photoresist layer 510, which can be
spin-coated onto the glass substrate 500. By exposing the photoresist 510
to a laser beam recorder or encoder (to be further discussed below),
features corresponding to pits 504, lands 506 and grooves 508 can be
formed in the photoresist after the exposed resist is developed in a
chemical solution, as illustrated in FIG. 5b. (For a positive
photoresist, areas exposed to the laser beam are removed by the
developer, forming the pits, while areas that are not exposed will
remain, forming the lands.) Dash lines in FIG. 5b represent various data
tracks, e.g., tracks 550 and 552 for pre-recorded data, with distance
between adjacent tracks denoted by a track pitch, p. In the case of a
DVD, the track pitch is 740 μm. In one embodiment, grooves 508 are
provided at various positions along the pre-recorded data tracks (e.g.,
tracks 556 and 558), and may be referred to as "on-track" grooves.

[0048] Alternatively, one or more grooves 508A may be positioned between
the data tracks, referred to as "off-track" grooves, which is shown in
FIG. 5d. Off-track grooves 508A, if present, are provided as a minimum of
two adjacent grooves, i.e., between pairs of adjacent pre-recorded data
tracks (e.g., 556-558 being one pair, and 558, 560 being another pair),
which allow proper tracking in order to record data on the spiral track
between the two off-track grooves, e.g., track 558. Grooves 508A may have
a separation or pitch (p') that is the same or different from the track
pitch (p) of the pre-recorded data tracks, and may also have a groove
depth that is different from that of grooves 508.

[0049] In these illustrations, recording grooves 508 and 508A have depths
less than the depth of pits 504 in the pre-recorded data area. In other
embodiments, the recording grooves may have a depth comparable to, or
larger than, that of the pits. In general, a recording groove has a
length at least as long as what is required for the appropriate data to
be recorded in the corresponding recordable area.

[0050] Grooves 508 and 508A may also co-exist on the same disc, as shown
in FIG. 5e, which illustrates a top view of a disc 570 according to one
embodiment of the present invention. The disc 570 has pre-recorded data
arranged in a spiral track pattern 572 (dashed line denotes additional
tracks that are omitted), with a lead-in region 574 and a lead-out region
576. On-track grooves 580, 582 and 584 (similar to 508 in FIG. 5b) are
provided in one or more recordable regions on tracks 572a, 572b and 572c
(i.e., following the pre-recorded spiral track pattern 572), while
off-track grooves 590, 592, 594 and 596 (similar to 508A in FIG. 5d) are
provided between adjacent pre-recorded data tracks. As mentioned,
off-track grooves, if present, are provided as at least a minimum of two
adjacent grooves (e.g., 590-592 pair, or 594-596 pair in FIG. 5e).
Furthermore, to enable proper tracking, an on-track groove and an
off-track groove cannot be directly adjacent to each other. Instead, at
least some pre-recorded data feature on a track should be located between
an on-track groove and an off-track groove, as shown in the example of
on-track groove 580 and off-track groove 590 positioned on either side of
pre-recorded data of track 572b.

[0051] Returning to FIG. 5b, after patterning the photoresist 510 with the
respective pits, lands and grooves, the glass substrate 500 with the
patterned photoresist structure is metallized by forming a thin layer of
metal 520, e.g., nickel, over the entire structure, resulting in a
metallized glass structure 530 as shown in FIG. 5c. The structure 530 is
then subjected to electroforming, which deposits additional metal onto
the metal layer 520 to form a stamper, such as stamper 400.

[0052] Different approaches may be used to perform the encoding of the
pits 504, lands 506 and grooves 508 in the glass master using one or more
encoders. In one embodiment, a dual-purpose encoder with two different
pattern generators (each having a different algorithm), one channel of
the encoder is used for encoding the program or user data, e.g., in the
program area 105 of FIGS. 1-2, as a standard pre-recorded disc, and a
second channel is used for encoding one or more recording grooves in at
least one recordable area, e.g., areas 110, 120 and 130 of FIGS. 1-2.

[0053] The dual-purpose encoder includes software and hardware that enable
seamless switching between the groove and data track recording as
required for this disc format. In one embodiment, a single wavelength is
used for encoding both data and grooves, e.g., using a blue laser at 405
nm.

[0054] Different recording groove structures and configurations, as well
as recording options in the pre-recorded and recordable regions, are
provided in different embodiments described below.

[0055] In one embodiment, one or more recording grooves in the recordable
areas are relatively shallow, e.g., less than about 100 nm. In another
embodiment, one or more groove may be less than about 50 nm, which is
suitable for use with a recording laser or device having a wavelength in
a blue-violet region. In another embodiment, the grooves and the
recording layer conform to a recording format described in an
international PCT patent application "Compatible Optical Recording
Medium", filed by Thomson Licensing, and published as WO 2008/043661A1,
on 17 Apr. 2008, which is herein incorporated by reference in its
entirety. This format, referred to as the Thomson Blue Laser Content
Scramble System (CSS) Recordable (BLCR) disc format, provides for
recording at one wavelength (e.g., 405 nm), and reading at a different
wavelength (e.g., 650 nm). The groove structure is designed to generate a
sufficiently strong push-pull (PP) signal at the recording wavelength to
allow tracking or guiding an optical pickup unit during recording, but
only a minimal or very weak PP signal at the reading wavelength.

[0056] Thus, a standard disc player operating at the reading wavelength
will not detect the presence of the recording groove, and the disc will
be treated as a read-only disc, which results in a high degree of
compatibility with most disc players (because some players have a copy
protection mechanism that renders a read-only disc unreadable if a PP
signal is also detected from a groove structure). In one embodiment, the
groove structure has a width of less than about 120 nm and a depth of
about 40 nm. In other embodiments, the groove may have a width in a range
of about 50 nm to about 250 nm, and a depth in a range of about 10 nm to
about 50 nm.

[0057] Although other groove configurations or formats may not offer as
high a degree of player compatibility as the BLCR format, they can also
be used in the context of the present invention.

[0058] Thus, in one example, one or more deep grooves, e.g., with a depth
of at least about 120 nm, are provided in at least one recordable area of
the disc. In this case, data (e.g., custom, control data or other
appropriate data) can be written to the recordable areas with a
conventional recorder, e.g., at a wavelength of 650 nm for DVD, since a
sufficient push-pull signal will be available for tracking with a red
laser pick-up head.

[0059] Another embodiment of the recording grooves is illustrated in FIG.
6a, which shows a top view of a disc 600 having one or more recordable
areas 610 and 620 between a lead-in area 604 and a lead-out area 606. In
this case, the grooves in the recordable areas 610 and 620 are
discontinuous grooves, consisting of long pits interrupted or separated
by short gaps or discontinuities in the groove.

[0060] FIG. 6b is a schematic illustration of a perspective view of two
discontinuous grooves 630, 640 in adjacent tracks. These grooves are
considered discontinuous because they have gaps (i.e., no groove, or
discontinuous section of the groove) along the length of the grooves,
e.g., gaps 632, 634, 642 and 644. In one embodiment, the gaps are
regularly spaced along the length of the groove, e.g., at a separation
(s), which can range from about 500 nm to about 2000 nm. Other
embodiments may have gaps that are not regularly spaced within a groove.
The length (l) of each gap or interruption is smaller than the resolution
of the red pick-up head, e.g., length l is less than about 200 nm, but
should be at least long enough to generate a sufficiently strong tracking
signal, e.g., DPD tracking signal, for recording purpose. In one
embodiment, it is expected that a gap length of at least about 75 nm will
suffice for DPD tracking. It is possible that the optimum gap length may
vary with the depth of the groove. The lengths of the gaps in a
non-continuous groove (or in different grooves) may be the same or
different.

[0061] It is expected that this non-continuous groove configuration will
allow the use of differential phase detection (DPD) tracking when
recording with a blue laser during the finalization process. In addition,
the discontinuous groove with DPD tracking can generally be used for
recording in other disc formats, i.e., not only in the finalization
process of a hybrid disc of the present invention, but also in other
conventional discs.

[0062] The use of non-continuous grooves in the recordable areas has the
advantage that DPD can be used for tracking the pre-recorded pits and the
grooves for recording, as opposed to having to switched to PP tracking if
continuous grooves were used in the recordable areas (since DPD tracking
does not work with continuous grooves).

[0063] In this embodiment, the grooves may have a depth ranging from about
10 nm to about 300 nm, and a width between about 50 nm to about 250 nm.
Additional data including, for example, custom or control data, may be
recorded on the grooves, e.g., at sample locations X anywhere inside a
groove, and/or at one or more locations at the gaps, e.g., gaps 632, 634,
642 and 644, as shown in FIG. 6b.

[0064] To provide effective DPD tracking, it is expected that many gaps be
provided in a groove, e.g., at least two gaps per groove. In one
embodiment, a gap separation (s) is less than about 10 μm (i.e., at
least one gap for every 10 μm along the groove), and in another
embodiment, the gap separation is about 0.5 to about 2 μm. The
dimensions of these gap separations are suitable for DVDs, and will vary
for other disc formats such as Blu-ray discs (BD) or CDs. The dimensions
for gap separations for other disc formats can be obtained by one skilled
in the art using appropriate scaling relationships.

[0065] There are certain scenarios under which a groove with one or more
gaps may not function with DPD tracking. These scenarios include
situations when only a single gap is provided in a groove, if the gaps
are provided at a separation considerably larger than 10 μm, or if a
gap is considerably smaller than about 100 μm, then the groove will
effectively serve as a continuous groove, in which case, PP tracking will
be required (DPD tracking will not be feasible).

[0066] FIG. 7a illustrates one embodiment of an optical disc 700, with a
lead-in area 704 and a lead-out area 706. The disc 700 also has at least
one blank section on a track in one or more recordable areas, e.g.,
sections 710, 720 and 730 that are left blank, i.e., without any pits or
recording grooves. If these blank recordable sections are relatively
short, e.g., having a length on the order of 100 μm or less, they are
not expected to affect tracking by a pickup unit because the inertia of
the pick-up unit will be able to keep the recording beam on track.

[0067] FIG. 7b is a schematic illustration of a perspective view of a
blank section 745 in a recordable area. In this example, blank section
745 is associated with track 740, and lies between pre-recorded pits 742
and 747. FIG. 7b also shows a track 750 adjacent to track 740, with
pre-recorded pits 752 and 754. The blank recordable section 745 has a
length (L) that is a few orders of magnitude larger than the gap (g)
between pre-recorded pits 752 and 754, e.g., length (L) is on the order
of 100 μm compared to gap (g) of about 0.4 to 2.0 μm. The length L
should be sufficiently long for recording appropriate data in the
corresponding blank section. In one embodiment, the length is sufficient
for recording a minimal data pattern, e.g., a bit of data. In another
embodiment, L is greater than about 10 μm. One embodiment also
provides for L being less than about 100 μm, and another embodiment
provides for L being greater than about 10 μm and less than about 100
μm. Unlike recordable section 745, the gap between 752 and 754 is a
part of the pre-recorded data stream, and is not recordable. In another
embodiment, it may also be possible that the blank section 745 lies
between two recording grooves on spiral track 740 (instead of
pre-recorded pits 742 and 747).

[0068] A unique signature may be generated by filling only certain blank
or gap sections (e.g., sections 710 and 730 of FIG. 7a) with appropriate
data, while leaving one or more other blank sections (e.g., section 720)
empty or filling them with uncorrectable data that would render these
gaps unreadable. The resulting pattern of readable and unreadable sectors
or sections (e.g., by introducing incorrect data) will represent a disc's
unique data content or serial number information, which may be used for
identification purpose. In this context, appropriate data refers to data
that matches error correction data or code that has been pre-recorded in
the relevant data sector (e.g., data that results in readable data and/or
sector). The proposed gaps or blank sections (without appropriate data
being recorded), will introduce too many errors to be correctable by the
error correction data. In addition, if the gaps are written with data not
matching the error correction data (e.g., inappropriate data), the sector
data will also be uncorrectable, thus rendering the sector unreadable.

[0069] In another embodiment, instead of writing data to one or more
recordable areas, the finalizing encoder can also write additional data
to one or more recordable areas having a recording medium over the
pre-recorded areas, e.g., by overwriting certain sections of pre-recorded
data, making those sectors unreadable. Again, the resulting pattern of
unreadable sectors can then represent unique data content for
identification purpose.

[0070] In another embodiment, a description of the data (e.g., metadata
required for the finalization process) that is written to the control
data area (part of the lead-in area) or other information area in the
finalization process may be stored in one or more pre-recorded sections
of the disc, preferably in an encrypted format. The description may
include the content of the data, as well as the location for recording
the data. Examples of pre-recorded sections suitable for storing such a
description include a portion of the lead-in area not containing other
control data, such as the "initial zone" for DVD, an unused section of
the program area (i.e., without pre-recorded data), or in the lead-out
area. By storing this information on the disc, there is no need for
connecting to a database to determine what needs to be recorded at which
location during the finalization process.

[0071] In yet another embodiment, instead of leaving the control data
section of the lead-in open, at least a portion of the file system
(different from control data), e.g., in the lead-in area, may be left
blank. With an incomplete file system, the program content on the disc
will not be readable. Thus, if proper or appropriate data is written to
complete the file system in a recordable region, the disc's content can
be made readable.

[0072] Since a conventional DVD recording device cannot be used for
recording data in the recordable areas of a disc manufactured according
to one or more of the present principles, a recording device is also
provided for this purpose. In one example, the recording device is a
custom laser having a wavelength in the blue-ultraviolet region of the
spectrum, which is designed for use with a 0.6 mm substrate such as that
for a DVD. If desired, the recording device may also be adapted for use
with other substrate thickness for different optical disc formats. In one
embodiment, the blue-ultraviolet laser is similar to that used in a high
definition (HD) DVD recorder, e.g., at a wavelength of 405 nm, which can
track on the recording grooves of the present principles and record the
lead-in/control data and custom data necessary to finalize or close the
recording of the disc. The recording device, which has special or custom
software or firmware, optical and electronic components designed for
recording in the recordable areas of the hybrid disc, may be modified
from a conventional HD DVD recorder pickup. Furthermore, it may be
possible to modify existing Blu-ray drives for this purpose by changing
to appropriate optics, including, for example, an objective lens with a
proper numerical aperture (e.g., 0.6) and with spherical aberration
compensation for 0.6 mm substrate thickness.

[0073] For example, the software or firmware (e.g., processor with program
stored thereon) on the recording device may provide instructions for
performing a method, which includes retrieving information for
identifying at least one recordable region on a disc, e.g., by at least
accessing pre-recorded data on the disc or accessing a database external
to the disc, and directing a laser to write additional data to the
recordable region. The method may also include an instruction for the
laser to track on a recording groove for writing the data. As previously
discussed, the recordable region(s) may be identified by one or more
sector numbers, signal characteristics and/or zone identifiers. Depending
on the specific configuration in the recordable region, different data
may be recorded for various purposes, e.g., to provide custom or unique
data for serialization or identification purpose, controlled activation
of a disc(to make the disc or program content readable), or to provide
updates or additions to the program content.

[0074] Although the above examples have focused on applications to DVDs,
embodiments of the present principles may be applied to CDs, BDs or high
definition/density (HD) DVDs, with suitable adaptations to the respective
recording formats and manufacturing materials to ensure that the final
disc meets the pre-recorded disc specifications, e.g., in accordance with
applicable standards.

[0075] One application in which optical discs of the present invention are
particularly valuable is the distribution of high value software that may
need to be uniquely serialized with purchase data (e.g. timestamp or
customer information). Using conventional techniques with standard
recordable media, a full recording session for the entire disc, i.e.,
including the program data and the purchase data, is required.

[0076] Embodiments of the present principles, however, enable hybrid discs
("recordable pre-recorded") to be quickly edited with relatively small
amount of custom data and lead-in information, which can be used for
serialization, security, product code, encryption key embedding, disc
activation or other applications, thus allowing publishers to uniquely
identify each pre-recorded disc at a machine-readable level. After
recording the additional data, the finalized disc can be recognized as a
pre-recorded disc by standard recorder and reader devices, thus enhancing
playback compatibility, e.g., especially on DVD-Video discs that are
protected with (CSS) copy protection. Other applications include addition
of unique serialization data used for the control of Managed Copy
applications (which allow consumers to make legal copies of
copy-protected digital content by obtaining authorization through a
remote server) and for the addition of retailer specific branding or
merchandizing campaigns.

[0077] Thus, the hybrid discs of the present invention have various
advantages over other conventional DVDs. For example, the additional or
customization data of this invention is likely to require a very small
recorded area, thus allowing for faster recording and reduced cost
compared to a full recording of DVD-R media. Although one supplier offers
proprietary technology for manufacturing a disc with a pre-recorded zone
containing a software program, and a recordable zone for adding a
customer's photographs (e.g., KODAK Picture CD), that technology does not
afford the ability to make the disc appear as if it were pre-recorded,
and thus, will not provide an advantage of improved player compatibility,
as can be realized by a disc of the present principles. Furthermore,
discs of the present invention offer a higher level of security to
publishers because the disc media is unique on a title basis, and access
to the pre-recorded, yet non-finalized or un-activated media can be more
tightly controlled.

[0078] Compared to DVD BCA Code, embodiments of the present principles
allow a larger portion of the DVD to be available as recordable area for
custom data, whereas the DVD specifications allow a maximum of only
188-bytes data to be stored in BCA code, which is insufficient for high
security encryption keys, Furthermore, implementations of the present
principles allow as much as 5 MB of custom data to be recorded in less
than 20 seconds, whereas other custom serialization technologies (e.g.,
Sony's post-scribed ID, or PID) have limitations on custom data storage
capacity, typically substantially less than 1 kB.

[0079] It is understood that the examples discussed herein are meant to be
illustrative, and one or more features of the present invention may be
implemented separately, or in various combinations with each other. Thus,
various embodiments of groove structure or configuration discussed above
may be implemented alone, or in conjunction with each other, for
recording one or more types of additional data. For example, a
pre-recorded disc may have grooves in recordable regions with different
depths, e.g., shallow grooves and deep grooves, or it may also include
both continuous and discontinuous grooves in different regions.
Furthermore, these features may also be implemented in different
configurations or formats of optical discs, including providing the
recordable area and pre-recorded area on the same layer or different
layers of a double-layer disc.

[0080] While the forgoing is directed to various embodiments of the
present invention, other and further embodiments of the invention may be
devised without departing from the basic scope thereof. As such, the
appropriate scope of the invention is to be determined according to the
claims, which follow.